Progress Bar for Blocks with Loop & Merge Function

Hi,
I am setting up an experiment in which I repeat a block with a loop & merge function for several times. I would like to have a progress bar that indicates the progress throughout all of these blocks (so not per block). However, the progress bar doesn't seem to work in combination with loop and merge. I also want it only for the blocks with the loop & merge, so not for other blocks.
I suppose I need JS to solve this issue, but I have no idea where to start. Perhaps anyone here could help me out?
I've added a a screenshot of the part of my flow where a loop & merge block is repeated.
Thanks :)